Biogenic nanosilver incorporated reverse osmosis membrane for antibacterial and antifungal activities against selected pathogenic strains: An enhanced eco-friendly water disinfection approach

Membrane Filtration technique is being accepted worldwide as an environment friendly and energy efficient technique in Desalination Industry as compared to Thermal Desalination techniques. However, the performance of membranes which include permeate flux and rejection is affected by the membrane fouling. The properties of membrane and surface features such as porous structure, hydrophilicity/hydrophobicity charge, polymer characteristics, surface roughness determine the fouling potential of the membrane. The hydrophilic and smooth membrane surface is usually considered desirable in tackling membrane fouling issues. Therefore, many studies have focused on to enhance surface characteristics of membranes by surface coating with polymers and nanomaterials. Since, membrane coating is not done during fabrication of the most commercially available membranes, therefore, it is also important to determine the surface features of the commercially available membranes to investigate their membrane fouling potential. Thus, the objectives of this study were (1) to perform membrane surface characterization of commercial Reverse Osmosis (RO) and Nanofiltration (NF) membranes using techniques such as SEM, AFM, FTIR and XPS; (2) to measure hydrophilicity/hydrophobicity of commercial RO and NF membranes through water contact angle measurement using sessile drop method and (3) to measure the flux and percentage rejection of NF and RO membranes using Dead end filtration technique. Here, the characterization of membrane surface in terms of surface roughness, using SEM and AFM, showed that the commercial RO membrane had more ridge and valley structures and higher average surface roughness i.e. 71.24 nm as compared to NF membranes (6.63 nm). In addition, water contact angle measurements showed that the NF membrane was more hydrophilic as compared to RO membrane. The average contact angle found for RO membrane was 59.94°. On the other hand, it was observed that NF membrane is extremely hydrophilic in nature. Due to which, contact angle value was not obtained for most of the runs. The droplet could diffuse in less than 5 seconds. In addition, the dead-end filtration experiments showed that the RO membrane had much lower flux as compared to NF membrane. This can be associated with the pore structure of these membranes. Since, the NF membrane has porous structure, in oppose to RO membrane, the flux of the NF membrane is usually higher than the RO membranes. As the membrane surface roughness and hydrophobicity makes it more susceptible to the fouling leading to reduction in membrane flux and performance, it can be concluded from this study that there is a need for surface coating of RO membrane with suitable nanomaterials such as graphene oxide to improve its hydrophilicity and surface smoothness. This will eventually make the membrane more resistant to membrane fouling and will establish the use of membrane filtration technique in desalination industry in Qatar in the future. Microorganisms have been isolated from Gulf sea water, identified and differentiated and are being used to study the biofouling of RO and NF membranes, that would be coated to limit the fouling problems. Acknowledgement: This research was made possible by NPRP grant # [9-318-1-064] from the Qatar National Research Fund (a member of Qatar Foundation). The findings achieved herein are solely the responsibility of the author[s].

Gold nanoparticles were prepared by green route using Couroupita guianensis leaves extract. The green synthesized gold nanoparticles exhibited maximum absorbance at 526 nm in the ultraviolet spectrum. By incorporating the green synthesized gold nanoparticles in poly(vinyl alcohol) matrix, unique green organic-inorganic hybrid nanofibers (poly (vinyl alcohol : )-gold nanoparticles) were developed by electrospinning. Contact angle measurements showed that the prepared poly (vinyl alcohol)-gold nanoparticles were found to be highly hydrophilic. The crystallinity of gold nanoparticles was analyzed using XRD. The synthesized gold nanoparticles and poly (vinyl alcohol)-gold nanoparticles were characterized using high-resolution transmission electron microscope, Fourier transform-infrared spectroscopy and energy-dispersive analysis of X-ray. The ultimate aim of the present work is to achieve optimum antibacterial, antifungal, biocompatibility and antiproliferative activities at a very low loading of gold nanoparticles. Vero cell lines showed a maximum of 90% cell viability on incubation with the prepared poly (vinyl alcohol)-gold nanoparticles. MCF 7 and HeLa cell lines proliferated only to 8% and 9%, respectively, on incubation with the poly (vinyl alcohol)-gold nanoparticles, and also exhibited good antibacterial and antifungal activities against test pathogenic bacterial and fungal strains. Thus, the poly (vinyl alcohol)-gold nanoparticles could be used for dual applications such as antimicrobial, anticancer treatment besides being highly biocompatible.

A simple and eco-friendly method for efficient synthesis of stable colloidal silver nanoparticles (AgNPs) using Mentha pulegium extracts is described. A series of reactions was conducted using different types and concentrations of plant extract as well as metal ions to optimize the reaction conditions. AgNPs were characterized by using UV-vis spectroscopy, transmission electron microscopy, atomic force microscopy, dynamic light scattering, zetasizer, energy-dispersive X-ray spectroscopy (EDAX) and Fourier transform infrared spectroscopy (FTIR). At the optimized conditions, plate shaped AgNPs with zeta potential value of -15.7 and plasmon absorption maximum at 450 nm were obtained using high concentration of aqueous extract. Efficient adsorption of organic compounds on the nanoparticles was confirmed by FTIR and EDAX. The biogenic AgNPs displayed promising antibacterial activity on Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. The highest antibacterial activity of 25 µg mL-1 was obtained for all the strains using aqueous extract synthesized AgNPs. The aqueous extract synthesised AgNPs also showed considerable antifungal activity against fluconazole resistant Candida albicans. The cytotoxicity assay revealed considerable anticancer activity of AgNPs on HeLa and MCF-7 cancer cells. Overall results indicated high potential of M. pulegium extract to synthesis high quality AgNPs for biomedical applications.

Myrtus communis is medicinal plant with the common name known as "Ades" in Ethiopia. Despite of its antimicrobial uses, there is limited study on antimicrobial activities of essential oil against pathogenic bacterial and fungi strains. The objective of the study is to investigate antibacterial and anti-fungal activity of Myrtus communis against pathogenic bacterial strains including; Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Staphylococcus aureus; fungi strains including Fusarium oxysporium and Asparegillus niger. The antibacterial activity was performed in vitro using agar disc diffusion assay and diameter of zone of inhibition was measured. The experiment was prepared in completely randomized design (CRD) with three replication. Calculations of antibacterial and antifungal activity were determined by mean value and standard deviation. Among all the extracts of n-hexane and methanolic extracts showed maximum antibacterial activity against E. coli and Staphylococcus aureus strain with a zone of inhibition ranges from 5.67-5.5 mm and the least activity was observed in chloroform and methanol extract with zone of inhibition range from 1-2.2 mm against Staphylococcus aureus. The test results were compared with standard antibiotics Chloramphenicol. On the hand chloroform possessed higher antifungal activity on Fusarium oxysporium with zone of inhibition value of 15.16 mm and the least zone of inhibition obtained from Methanol with zone of inhibition value of 4.75 mm. The minimum inhibitory concentration (MIC) was conduct only for n-hexane extract because of its higher inhibition value than other solvents. The MIC value ranges from 3.125 mg/mL to 12.5 mg/mL. The results suggest that n-hexane and methanolic extracts of Myrtus communiscan be used in the treatment of infection caused by E.coli and Staphylococcus aureus strains and chloroform extract also used in the treatment of infection caused by Fusarium oxysporium.

A series of twenty compounds (23-42) were synthesized and characterized by spectral studies in order to explore newer antimicrobial compounds. The majority of the synthesized compounds reported significant antimicrobial properties against various pathogenic bacterial and fungal strains with the help of tube dilution method. Significant activities (MIC ranging from 3.9 to 15.62 μg/ml) have been shown against Gram-negative and Gram-positive bacteria with. In contrast, moderate to outstanding antibacterial activity was reported versus Gram-negative bacteria such as E. coli and P. aeruginosa along with Gram-positive bacteria such as S. aureus and B. subtilis. While antifungal activity was moderate to excellent against two fungus strains (Candida tropicalis, Candida glabrata). Compounds 25 and 34 had the utmost activity versus Gram-positive and Gram-negative bacteria too. The antifungal activity of compound 35 was comparable to that of standard. In-silico Molecular docking evaluations were performed for antibacterial and antifungal activities against the target DNA gyrase A (PDB: 1AB4) and 14 alpha-sterol demethylase enzyme (PDB: 1EA1), respectively. The dock score for typicals compounds for antibacterial and antifungal activity were -4.733 and -9.4, respectively. The three-dimensional QSAR examination was carried out by multiple linear regression (SA-MLR) with good predictive power (r2=0.9105, q2=0.8011). Establishment of several interactions between the ligand 25 and 34 and the active site of residue of both receptors, enable the ligand 25 and 34 to be fit well in the pocket of the active site, as seen in Molecular dynamics simulations analysis. Thus, data suggest that these ligands could be further explored as potential precursors to develop antimicrobial drugs.

Objective: The current study exemplifies the synthesis of silver nanoparticles using Muntingia calabura L. (Mc-AgNP’s) fruit extract utilizing a green approach and testing the efficacy of synthesized NP’s. Methods: The green synthesize approach was used to synthesis Mc-AgNP’s followed by characterization using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Energy Dispersive X-ray Spectroscopy (EDX), and Field Emission Scanning Electron Microscopy (FESEM). Radical scavenging activity was assessed using DPPH, FRAP, and H202, followed by antibacterial activity. Results: The characteristic features of synthesized Muntingia calabura silver nanoparticles (Mc-AgNP’s) were analyzed using FT-IR which particularizes different functional groups with a broadband at 3408 cm-1 representing hydroxyl (-OH) stretching a peak at 1593.27 cm-1 corresponds to C = O groups in amide whereas a dip at 1383 cm-1 represents C-N amine and C-O stretching of alcohol groups were found. The Crystallinity of synthesized Mc-AgNP’s exhibited face-centered cubic (fcc) crystalline structure and the bio-reduction of the silver ions in solution was monitored by Energy dispersive X-ray spectroscopy (EDX). The FESEM analysis indicates that Mc-AgNP’s were dispersed in the solution using micrographs and the size ranged from 10 to 60 nm. The synthesized Mc-AgNP’s efficiently scavenged free radicals in a dose-dependent manner with 69% for DPPH, 59.9% for FRAP, and 64% for H202 respectively. Further, the synthesized Mc-AgNP’s demonstrated a potent antimicrobial agent against tested bacterial and fungal strains with a maximum zone of inhibition observed in S. aureus, K. pneumonia, and P. vulgaris with 14.6, 13.8, and 12.4 mm. Similarly, antifungal activity with Trichoderma harzianum demonstrated the highest zone with 18 mm followed by Aspergillus oryzae with 7 mm. Conclusion: These results highlight the interesting potential of synthesized Mc-AgNP’s as an effective source of bioactive compounds with potent antioxidant and antibacterial activity.

Different medicinal plants have the potential of antibacterial and antifungal activities. Therefore, this research was executed to assess the antibacterial and antifungal activities of different fractions i.e. water (H2O), chloroform (CHCl3), n-hexane (C6H14) and ethyl acetate (C4H8O2) of Convolvulus leiocalycinus and Haloxylon griffithii by applying Agar well diffusion method. Bacterial strains of four types i.e., 3 gram-negative and 1 gram-positive namely Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, Pseudomonas aeruginosa and a fungal strain like PBF-1 were used to investigate the antibacterial and antifungal activities in the selected plant extracts. The water, chloroform, ethyl acetate and n-hexane fractions of C. leiocalycinus exhibited antibacterial activities of 7, 7, 7 and 6mm zone of inhibition respectively against S. aureus bacteria. Consequently, the same four fractions of H. griffithii displayed antibacterial activities against S. aureus 8, 8, 9 and zero mm zone of inhibition respectively. Considering the antifungal activity, the ethyl acetate fraction of C. leiocalycinus showed strong inhibition i.e., ++. But in H. grifithii, only the n-hexane fraction gave partial inhibition in antifungal activity. These results indicated that the ethyl acetate fraction of C. leiocalycinus exhibited strong antifungal activity as compared with the same fraction of H. griffithii showing that C. leiocalycinus is more potent as compared to H. griffithii. This justifies the usage of both plants in traditional medicines in future. It is also suggested that the use of entire extract of both the plants in foods can improve their shelf life. Keywords: Agar well diffusion; Antibacterial activity; Antifungal activity; fungal strain PBF-1. http://dx.doi.org/10.19045/bspab.2019.80175

Crocus sativus L. commonly known as saffron or Kesar in India, is an important medicinal herb in Ayurveda and has been traditionally used for treatment of neurological disorders, for depression, anxiety and sleep disorders. It is uses as a coloring and flavouring agent in the preparation of various foods. Modern research has high lighted its beneficial effects in treatment of cardiovascular action, diabetic cataract, and as a potent antiinflammatory herb. Due to its high cost its quality control is of utmost importance to ensure its authenticity, purity and its medicinal properties. In the preset study the we have used Thin Layer Chromatography (TLC) analysis, High performance thin layer chromatography (HPTLC) fingerprint, UV-Vis spectrophotometric analysis, 1H nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectroscopy (FTIR) based metabolomic study for quality control and characterization of saffron. The antibacterial and antifungal activity were evaluated using agar well-diffusion method in two pathogenic bacterial strains, Escherichia coli, Staphylococcus aureus and two pathogenic fungal strains, Candida albicans, and Aspergillus brasiliensis. The 1H NMR spectroscopy couples with FTIR analysis leads to identifcation of the secondary metabolites of saffron like crocetin, picrocrocin and safranal on basis of reported diagonostic signals and peaks. The antimicrobial activity showed moderate antibacterial and antifungal activity. The TLC and HPTLC profile reveals the characteristic fingerprint. Overall the present study showed that the 1H-NMR, FTIR based metabolomics approach and TLC and HPTLC metabolite profiling can be powerful strategy for maintaining the holistic quality of the saffron.

PEG-coated reverse osmosis membranes: Desalination properties and fouling resistance

Probing the nano- and micro-scales of reverse osmosis membranes—A comprehensive characterization of physiochemical properties of uncoated and coated membranes by XPS, TEM, ATR-FTIR, and streaming potential measurements

The present study was considered to assess the antibacterial and antifungal activity of seagrass, Thalassia hemprichii extract against pathogenic bacterial and fungal strains. The seagrass T. hemprichii was collected from Gulf of Mannar, Tuticorin coast, Tamil Nadu. The collected seagrass samples were air dried and extracted with ethyl acetate, diethyl ether, acetone, methanol, ethanol and water. The acetone and ethanol crude extract of T. hemprichii exhibited broad spectrum antibacterial and antifungal activity when compared to other crude extracts. Acetone and ethanol crude extracts were further fractionated and purified using column chromatographic technique. The purified bioactive fractions (F6-A: M, F5-E) showed significant antibacterial and antifungal activity. The purity of separated fractions was analyzed using high performance liquid chromatography. The acetone extracted, column chromatographic separated fraction (F6-A: M) possess bactericidal single bioactive compound. From these results it can be concluded that seagrass T. hemprichii has a potential bioactive metabolic compound to inhibit the pathogenic bacterial and fungal strains.

Cyanobacteria are known to be a rich source of biologically active compounds some of which can have pharmaceutical importance. In this work we present the screening results of cyanobacterial strains for their antibacterial, antifungal, and cytotoxic activity. Cyanobacterial strains were isolated from various soil types in province of Vojvodina and Central Serbia, Republic of Serbia. The screening included 9 strains of Anabaena and 9 strains of Nostoc. Both, extracellular products (from the culture liquid) and cellular crude lipophilic extracts were tested against 13 bacterial strains and 8 fungal strains. Cytotoxic activity was tested against three human cell lines. Methanol extracts were prepared according to Østensvik. Antibacterial and antifungal activities were determined measuring inhibition zone, 48 h after inoculation. The cytotoxic activity was determined by sulforhodamine B (SRB) colorimetric assay. Of all cyanobacterial strains tested, 52% showed some antifungal and 41% antibacterial activity. Two out of six tested strains possessed cytotoxic activity. The cytotoxic activity of Anabaena strain S12 was found both in culture liquid and crude cell extract. It occurred specifically between the 21st and 42nd day of cultivation against HeLa and MCF7 cells, but had no activity against cell line derived from a healthy tissue. A high percentage of the active strains among the tested strains justify the effort of screening cyanobacteria that are isolated from terrestrial environments. The most promising strains for the further study are Anabaena strain S12 which showed strong cytotoxic and antibacterial activity and Anabaena strain S20 which produces a potent antifungal compound. The future work, besides further screening and chemical identification of the active compounds, should also include the development of culture techniques that would lead to more efficient production of biologically active compounds.

Introduction. A lot of plant produced essential oils, which are applied in prophylaxis and therapy of medicine. Melissa was known and used in I century BC. It produced the oil, which possess following properties: antiarteriosclerotic, anticancer, sedative, antidepression, antimigraine, antiasthmatic, antirheumatic and antioxidant. Its contain: geraniol, β-caryophyllene, geranial, thymol, neral, geranyl acetate, linalol, cytronellol, citronellal and α-humulen. It exhibited antibacterial and antifungal activity. Aim. The aim of this study was to indicate of susceptibility of yeastlike fungi to melissae essential oil. Material and methods. The strains of fungi were isolated from oral cavity from patients with candidosis. A total 23 strains of yeastlike fungi from genus of Candida albicans (22 strains), C. glabrata (5), C. guilliermondii (2), C. humicola (2), C. kefyr (3), C. krusei (5), C. lusitaniae (2), C. parapsilosis (5), C. tropicalis (6), C. utilis (1) and 9 reference strains were tested. Investigated was carried out using plate dilution technique in Sabouraud’s agar. The melissae oil (Semifarm) was dissolved in DMSO and then in aseptic distilled water. Inoculum contain 105 CFU per spot was transferred with Steers replicator upon the agar with and without essential oil (strains growth control). The concentrations of melissae oil were: 2.0, 1.0, 0.5, 0.25 and 0.12 mg/ml. Incubation was performed in aerobic conditions in temp. 37°C. Incubation of agar plates were performed in aerobic condition at temp. 37°C, at 24-48 hours. Minimum inhibitory concentration (MIC) was interpreted as the lowest concentrations of melissa oil which inhibited the growth of yeastlike fungi. Results. The dates indicated that the strains of fungi was susceptible to oil in concentrations 0.25-2.0 mg/ml. The 19 (86%) of strains from genus Candida albicans was inhibited in concentrations 0.25-0.5 mg/ml. On the same values of MIC’s were susceptible the strains of Candida albicans, Candida glabrata and Candida humicola (MIC 0.5 mg/ml). The fungi from genus of Candida kefyr, Candida krusei, Candida lusitaniae and Candida tropicalis were less sensitive. The growth of this yeastlike fungi was inhibited by concentrations of melissae oil in range 0.5-2.0 mg/ml. The oil was the lowest active towards genus Candida lusitaniae and Candida utilis. The MIC for these strains was from 1.0 to 2.0 mg/ml. From all tested genus Candida strains 11 (21%) of them was susceptible to melissa oil in range 2.0 mg/ml. Conclusions. Melissa oil was the most active towards strains of Candida albicans, Candida glabrata and Candida humicola. The lowest sensitive to oil were the strains from genus Candida lusitaniae and Candida utilis. The melissa oil characterized a high activity towards all tested strains of yeastlike fungi from genus of Candida.

The polyamide reverse osmosis (RO) membrane was modified with graphene oxide (GO), followed by polymerization of acrylic acid (used as an antiscalant) for the reduction of both biofouling and mineral scaling. After functionalization, the water contact angle reduced from 41.7 ± 4.5° for unmodified RO membrane to 24.4 ± 1.3° for the modified RO membranes, which showed that membrane hydrophilicity was significantly enhanced, in addition to the improvement in surface smoothness. The modified membranes were tested for their anti-scaling and anti-biofouling characteristics. When the mineral scaling test was performed using CaSO4 solution as feedwater, the permeate flux was reduced by only 3% as compared to the unmodified RO membrane which encountered up to 22% decline in flux by the end of the experiment. After the scaling test, the membrane surface was characterized by Scanning electron microscopy – energy-dispersive X-ray spectroscopy, Fourier transform infrared, and X-ray diffraction techniques. The results showed that the unmodified RO membrane was fully covered with gypsum precipitates. Whereas, the precipitates were detected only at the highly saturated zones of the water channel i.e. towards the exit of water flow. Additionally, the anti-bacterial test was performed through bacteriostasis rate determination, which showed that the modified membranes inhibited the growth of nearly 95% of the bacterial cells. Further experiments were also performed to investigate the inhibition of both scaling and biofouling by modified RO membranes. Thus, it was found that the polymer-modified GO coated RO membranes were able to diminish both gypsum scaling and biofilm formation demonstrating their potential to control different types of membrane fouling.

The emergence of multidrug microbial resistance is the main challenges that the modern scientists have so far been facing in the recent era. In this respect, new series of drug classes having potential to give antimicrobial effect have been synthesized. A new series of 5- substituted-1,10 b-dihydroimidazole[1,2-c]quinazoline derivatives 8a-e have been synthesized and screened for antibacterial activity and antifungal activity. Synthesized derivatives were characterized by IR, MASS and 1H-NMR spectroscopy. Synthesized compounds show good activity, which was comparable to the standard drug and it can be useful for the further clinical study. Antibacterial activity was evaluated against four different pathogenic bacterial strains like Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudo-monas aeruginosa. Among the screened compounds, 8e show good antibacterial activity against Staphylococcus aureus and Escherichia coli with MIC of 50 and 100 μg/ml respectively. Antifungal activity was evaluated against two strains of fungi. Among the synthesized derivates, compound 8c was emerged out as the potent antifungal compound against Candida albicans and Aspergillus niger with MIC of 25 μg/ml and 75μg/ml respectively. Compound 8e also shows good antifungal activity with MIC of 50 μg/ml against both Candida albicans and Aspergillus niger. The overall results of this study indicated that synthesized quinazoline derivatives had the potential to act as an antibacterial and antifungal agent, hence further investigation is warranted.